The Southern Island (Japanese: みなみのことうSouthern Island) is an island located south of Hoenn. In Pokémon Ruby, Sapphire, and Emerald, the player can only gain access to Southern Island through use of the Eon Ticket. To obtain the Eon Ticket in Ruby and Sapphire, the player must either connect their game to an e-Reader and scan the physical Eon Ticket and then talk to Norman who gives the ticket, or mix records with a player who has done the former. The second option is the only available method to obtain the Eon Ticket in Pokémon Emerald. The physical ticket was distributed in Nintendo Power volume 173.

Once the event has been activated, in order to be given passage to Southern Island, the player, beforehand, must travel to Lilycove City and attempt to board the S.S. Tidal. From there, the player will be taken to Southern Island. Upon examining an object found deep in the forest on the island, the player will then be engaged in battle with either a wild Latias or Latios (whichever was not found roaming Hoenn in the wild), at level 50 and holding the item Soul Dew. The player is not permitted to return to Southern Island after battling this Pokémon in Ruby and Sapphire.